Tom and Sophie Huff

Inquiring Minds: Troubled Waters

Antibiotic-Resistant Bacteria in Nearby Waterway Causes Great Concern

By Lynn Burke

Tom Huff, M.S. Chemistry '97, and other researchers in George Mason's Shared Research Instrumentation Facility (SRIF) are taking a close look at antibiotic-resistant bacteria they have found in Maryland's Pocomoke River with the long view that their research will shed light on the problems that have plagued the river and other Chesapeake Bay tributaries in recent years.

According to Huff, the SRIF lab manager and a doctoral student in George Mason's Environmental Science and Public Policy program, the university's interest in the Pocomoke, part of the Chesapeake Bay watershed, began several years ago when the river was experiencing massive fish kills, which at the time were attributed to the organism Pfisteria.

"This interested us, so we began doing what we could to see if we could come up with any answers for what's going on in that vicinity," says Huff. "What we are finding, along with many other people, is that it's a very sick river.

"Part of the problem is that the river's ecology has been turned on its head," says Huff. The river is right in the middle of a major poultry-producing region, he explains, and the farmers don't have an adequate way to deal with all the manure. Typically, the nutrient-rich manure is composted and then spread on nearby fields. When it rains, anything in the manure ends up in the runoff that eventually reaches the river. The resistant bacteria that George Mason researchers have found may indicate that antibiotics, which are given to the chickens in therapeutic doses in their feed, are persisting in their manure and ending up in the Pocomoke.

Along with killing off bacteria that is beneficial to the ecosystem, antibiotics also cause problems when they come in contact with potentially harmful bacteria that can withstand low doses of antibiotics. "The ones that don't die continue to reproduce, and you end up with a large population of bacteria that has developed a resistance to specific antibiotics, and that's when things start to go wrong," says Huff. When you have a recreational area like the Chesapeake Bay, if a boater, water skier, or swimmer has a cut and goes into the water, he or she can be infected by this resistant bacteria and the usual cure'antibiotics'won't be of much help, he adds.

According to Jenefir Isbister, a research professor in SRIF and George Mason's Center for Bioresource Development, many antibiotics are not degraded when they enter the environment or come through a wastewater treatment plant. The research team, which also includes Huff's wife Sophie, a Biology graduate student at George Mason, will be looking at how different land-use practices affect the number and diversity of microbes in the water. For instance, says Isbister, chicken farms use a lot of sulfanomides and that's where the team found bacteria resistant to sulfanomides; near an aquaculture facility where a lot of tetracyclines are used, they found bacteria resistant to tetracyclines.

"Our interest is to see what types of antibiotics are in the water and the sediment to get an idea of what's going on. The problem is that it hasn't been done that often," says Huff. Methods for determining how much of the common pollutants--such as pesticides, PCBs, and dioxins--have been developed, he says. "The problem with antibiotics is that the methods are not in existence yet."

According to Huff, several groups are making progress, but, at this point, no one can sample water or sediment and tell you all the antibiotics in the sample. Part of the SRIF research is to develop methods to test for a large number of antibiotics. The researchers are approaching this task in two ways: the SRIF microbiologists look for bacteria resistant to specific antibiotics, and the SRIF chemists confirm the presence of those antibiotics and determine their concentration in the environment.

So far, the team has found a great deal of antibiotic-resistant bacteria in the river. "That's not a very comforting thought," says Huff, "especially with people swimming around out there."

For more information, call Huff at (703) 993-1255 or send e-mail to thuff@gmu.edu.